Heat Transfer Enhancements at Low-Pressure for Electromechanical Actuators

In aerospace applications, the electronic components of aircraft must endure drastic changes in ambient conditions. The changes in ambient vary from 101.325kPa to approximately 20% and 30% of the atmospheric condition at cruising altitude. Electromechanical actuators (EMAs) analyzed in the current work generate heating loads of up to 1000W of heat for a cylindrical volume of 6.95×10 ⁵ mm ³ . Coupling the high-altitude effects with the thermal loads requires innovative cooling schemes to ensure that EMA operates at feasible temperatures at any point during its function. The effects of radiation and convection are analyzed to determine the dominant mode of heat transfer for maximum heat dissipation. CFD was used as a tool to examine the various conditions and parameters in the current paper. Increasing Re enhances the cooling capacity drastically by lowering the maximum temperature by 40% but is limited to the source generating the fluid motion. Low-pressure conditions indicate that thermal radiation is the dominant mode of heat transfer and introducing convective heat transfer modifications at the low-pressure conditions significantly improves the heat extraction from the EMA. Solid reduction schemes lower the weight and maximum temperatures of the solid; moreover, a circular slotted design enhanced the performance by nearly 5% and 4%, respectively. Inserting cooling passages with polyalphaolefin (PAO) greatly reduced the peak temperature of the solid by 55% to operable temperatures of the heated substrate. Finally, the paper highlights the various parametric enhancements to analyze the two modes of heat transfer for heat dissipation with a special emphasis to improve the convective heat flux by introducing cooling passages to maximize the heat extraction from the solid substrate.